1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method and a computer program and, in particular, to an image processing apparatus, an image processing method and a computer program for displaying a subject in an image on a display screen of a television receiver or the like with similarity of the subject maintained while effectively utilizing the display screen.
2. Description of the Related Art
There are a number of images different in aspect ratio, pixel count, and image format. More specifically, an image having an aspect ratio of 4:3 (hereinafter referred to as 4:3 image) and an image having an aspect ratio of 16:9 (hereinafter referred to as 16:9 image) are in widespread use.
A number of display devices such as TV receiver for displaying an image are different in aspect ratio, pixel count, and screen format of a display screen. More specifically, a display device with a display screen having an aspect ratio of 4:3 (hereinafter referred to as referred to as 4:3 screen) and a display device with a display screen having an aspect ratio of 16:9 (hereinafter referred to as 16:9 screen) are in widespread use.
When an image is displayed on a display screen having the same aspect ratio as that of the image, for example, when the 4:3 image is displayed on the 4:3 screen, or when the 16:9 image is displayed on the 16:9 screen, the image is displayed on the entire screen. Any subject appearing in the image is displayed on the display screen with similarity thereof maintained.
If the aspect ratio of the image is different from the aspect ratio of the display screen, the display screen cannot be fully utilized.
FIGS. 1A and 1B illustrate display examples in which an image is displayed on a display screen having an aspect ratio different from that of the image.
FIG. 1A illustrates the display example in which a 16:9 image is displayed on a 4:3 screen.
When the 16:9 image is displayed on the 4:3 screen, the 16:9 image is associated with black bands thereabove and therebelow on the 4:3 screen due to the difference between the aspect ratio of the entire area of the 16:9 image and the aspect ratio of the 4:3 screen. Such a display is referred to as a letterbox.
When the 16:9 image is displayed on the 4:3 screen, the black bands on the top and the bottom portions of the 4:3 screen become extra areas unused for displaying input image (having a value as information).
FIG. 1B illustrates the display example in which the 4:3 image is displayed on the 16:9 screen.
When the 4:3 image is displayed on the 16:9 screen, the 4:3 image is associated with side panels as black bands on the 16:9 screen due to the difference between the aspect ratio of the entire 4:3 image and the aspect ratio of the 16:9 screen.
When the 4:3 image is displayed on the 16:9 screen, the black bands on the left end and right end portions of the 16:9 screen remains unused.
When the image is displayed on the display screen different in aspect ratio from the image, the extra areas serving no purposes are caused, and the display screen is not fully utilized.
Japanese Patent No. 2759727 discloses one technique. In accordance with the disclosed technique, the 4:3 image is converted into an image having an aspect ratio of 16:9 by expanding the 4:3 image horizontally in order to display the 4:3 image on the 16:9 screen. The 4:3 image is thus displayed on the entire 16:9 screen.
Japanese Unexamined Patent Application Publication No. 9-163260 discloses another technique. In accordance with the disclosed technique, a sub screen is arranged to display a specified portion of a main screen in an expanded or contracted scale. Signals displayed on the main screen and the sub screen are different. In accordance with the disclosed technique, the portion of the main screen is displayed on the sub screen in a picture in picture (PinP) fashion in an expanded or subtracted scale. The portion of the main screen is thus hidden.
Japanese Unexamined Patent Application Publication No. 2006-33380 discloses another technique. In accordance with the disclosed technique, a location of interest in an image being captured by a monitor camera, is displayed on a main screen. The location of interest is displayed on the sub screen external to the main screen. In accordance with the disclosed technique, a substantial area of a display is not used, and thus the display area is not effectively used.